In the search for improvements in the operation of internal combustion engines, many attempts have been made to replace the conventional poppet valves of an engine cylinder with rotary valves. One such attempt is illustrated in U.S. Pat. No. 1,692,396. Another, more recent, engine design utilizing rotary valves is shown in an article by David Scott, relating to a cruciform engine, beginning on page 78 of the July, 1975 issue of Popular Science.
These, however, are mrely exemplary of the hundreds of patents and articles relating to the use of rotary valves in engines.
Rotary valves have been considered to have significant advantages over the conventional poppet valves for an engine cylinder because they can operate more rapidly, reducing the problem which can be found in high speed poppet valve engines, in which the poppet valve actually can tend to run behind the remainder of the engine, the valve return springs being inadequate to cause them to keep up with the operation of the engine at an extremely high RPM rate.
Also, the maximum compression of an engine must be limited so that the piston at top dead center position does not strike the open poppet valve. If one desires to increase the compression beyond such a level, it would be desirable to use rotary valves.
Furthermore, in many designs of rotary valves, a single port, functioning as both fuel inlet and exhaust gas outlet, can be provided to the combustion cylinder. This reduces the extremely high temperatures of the exhaust valve in a conventional poppet valve engine, reducing the possibility of preignition upon compression of the fuel mixture prior to firing.
Rotary valves also require less energy to operate than poppet valves, increasing the energy output of the engine.
However, despite the various significant potential advantages that a rotary valve system can be expected to have in an internal combustion engine, they have not come into commercial use, largely because rotary valves tend to leak if they are loose enough to permit free rotation, but they may seize if they are tight enought to contain the combustive pressures generated in the combustion chamber. To date, there appears to have been proposed no effective way to seal rotary valves in such a manner that the leakage of fuel vapors and exhaust gas is prevented to such a degree over the long term that the commercialization of a motor using a rotary valve system would be feasible.
In accordance with this invention, a rotary valve system having an auxiliary sealing mechanism is provided, particularly for sealing of the combustion chamber during compression and ignition states of motor operation.
As a result, the rotary valve itself no longer has to perform a significant sealing role against the pressures of the combustion chamber, but may simply work as a metering device for fuel and exhaust gas at relatively ambient pressures. Thus, the problem of rotary valve seizing can be eliminated, since the critical sealing functions are provided by other means.
Thus, the many advantages of the rotary valve may be utilized in motors designed in accordance with this invention.